RESUMO
CO2 conversion to CO by reverse water-gas shift using chemical looping (RWGS-CL) can be conducted at lower temperatures (ca. 723-823 K) than the conventional catalytic RWGS (>973 K), and has been attracting attention as an efficient process for CO production from CO2. In this study, Co-In2O3 was developed as an oxygen storage material (OSM) that can realize an efficient RWGS-CL process. Co-In2O3 showed a high CO2 splitting rate in the mid-temperature range (723-823 K) compared with previously reported materials and had high durability through redox cycles. Importantly, the maximum CO2 conversion in the CO2 splitting step (ca. 80%) was much higher than the equilibrium conversion of catalytic RWGS in the mid-temperature range, indicating that Co-In2O3 is a suitable OSM for the RWGS-CL process.
RESUMO
Efficient activation of CO2 at low temperature was achieved by reverse water-gas shift via chemical looping (RWGS-CL) by virtue of fast oxygen ion migration in a Cu-In structured oxide, even at lower temperatures. Results show that a novel Cu-In2O3 structured oxide can show a remarkably higher CO2 splitting rate than ever reported. Various analyses revealed that RWGS-CL on Cu-In2O3 is derived from redox between Cu-In2O3 and Cu-In alloy. Key factors for high CO2 splitting rate were fast migration of oxide ions in the alloy and the preferential oxidation of the interface of alloy-In2O3 in the bulk of the particles. The findings reported herein can open up new avenues to achieve effective CO2 conversion at lower temperatures.
